Windshield wiper assembly with a noise and vibration-damping fastener

ABSTRACT

A noise-damping or vibration-damping attachment feature for a windshield wiper system includes a damping element which is located in an opening of an attachment section of the windshield wiper system and itself supports, in a passage opening, a casing to hold an attachment screw or an attachment bolt, and to refine the aforesaid attachment feature in such a manner that it can be produced at low cost while dispensing with a manual mounting of the damping element. The attachment section and the bushing are manufactured as a single part from the same material, wherein the bushing connected by means of ridges at least temporarily to the attachment section, and the damping element is poured or injected into the space between bushing and attachment section.

The invention pertains to a windshield wiper system with a noise-dampingor vibration-damping attachment feature for attachment to a vehiclechassis according to the preamble of claim 1.

From DE 4,036,367 A1 a preassembled windshield wiper system is knownwhose motor support plate and wiper bearing housing is equipped withattachment features for noise-damping or vibration-damping attachment tothe vehicle chassis. The wiper bearing housing has a lateral moldedprotrusion that has an attachment section with a passage opening. At theedge of a motor support plate which belongs to the windshield wipersystem there is likewise an attachment section with a passage opening.There is a hollow, cylindrical damping element made of resilientmaterial and having an annular groove running along its outer perimeterin the passage openings of the aforesaid attachment sections. The ringgroove is located roughly in the longitudinal center of the dampingelement. There is a metal bushing used to hold an attachment bolt or anattachment screw installed in the central passage opening of the dampingelement.

A disadvantage of these known attachment features is that the insertionof the damping elements into the attachment sections and of the casinginto the damping elements has to be done manually and thus represents acost-intensive and complicated assembly process.

From DE 3,903,976 A1 another preassembled windshield wiper system isknown which contains a motor support unit produced as a pressure-castarticle. Molded onto the motor support unit is a lateral attachmenteyelet, designed to be open at one edge so that a resilient dampingelement of the kind described in DE 4,036,367 A1 can be inserted fromthe side into the passage opening. This design does indeed result in asimplification with regard to the insertion of the damping element intothe passage opening of the attachment section, however, here too, thedisadvantages stated above still apply.

Therefore the purpose of the invention is to refine a windshield wipersystem of the type described above in such a manner that thenoise-damping or vibration-damping attachment feature can bemanufactured at low cost, while dispensing with a manual assembly of thedamping element and of the casing to the attachment section.

According to this invention, the problem is solved by a windshield wipersystem with the features of claim 1.

The basic idea underlying the invention consists in that the dampingelement, which is manufactured preferably as a rubbery element fromelastomeric material, is cast or injected-molded directly into therelevant position for it in the attachment section of the correspondingsupport portion of the windshield wiper system. Or stated in otherwords, the damping element is cast or is injected immediately after itsmanufacturing process into the space between the required bushing andthe passage opening of the attachment section. This method has theadvantage that a complicated preliminary assembly by snapping aprefabricated damping element into the passage opening of the attachmentsection and the installation of the bushing into the passage opening ofthe damping element can be omitted.

Because the bushing is manufactured as a single piece together with theattachment section or the corresponding component of the windshieldwiper system which has the attachment section, there is a cost advantagewith respect to the manufacture of this part of the windshield wipersystem, and the insertion of a separate bushing into a correspondingmolding tool for the purpose of casting or injection with the dampingelement can be omitted. The ridge or the ridges which connect thebushing as a single piece to the attachment section are essentiallyintended to hold the bushing in its predefined position for theinjection of the damping element. In order, on the other hand, toprevent the transfer of solid-borne sound or vibrations, which willoccur during operation of the windshield wiper system to the bushing andthus to the vehicle chassis, the ridges must be constructed so that theywill not transmit, or will transmit at most a negligible amount, of thesolid-borne sound or vibrations. Accordingly, the ridges are constructedso thin and are shaped such that they output their vibrational energyessentially to the damping element which surrounds them, and not to thebushing.

It is also possible for the ridges to connect the bushing for only alimited time, that is, temporarily, to the attachment section of thewindshield wiper system. Expressed differently, this means that theridges are designed so that they are consciously broken off afterperforming their positioning task. According to one favorable design ofthe invention, set fracture points are located in the ridges for thispurpose. The breaking of the ridges occurs either after a certainoperating time of the windshield wiper system, or the breaking iseffected by tightening the windshield wiper system to the vehiclechassis by means of appropriate, brief application of mechanical force.Since the parts of the ridges after the break are no longer joinedtogether, they likewise cannot transmit any solid-borne sound orvibrations from the windshield wiper system to the bushing.

The advantage is that the particular support part of the windshieldwiper system which has the attachment section can be manufacturedaccording to requirement, either as a cast article and, preferably inthat case, as a pressure-cast article using a suitable metal or asuitable metal alloy, or even as an injection-molded article using asuitable plastic. The damping element in this case can be injectedaround the bushing into the attachment section of the windshield wipersystem using a two-component technology.

Claims 2 to 7 specify several favorable embodiments which are directed,either individually or in combination at positioning the bushingaccurately and dependably in the passage opening of the attachmentsection of the windshield wiper system, and in addition, at most anegligible transmission of solid-borne sound or vibrations will betransferred from the windshield wiper system to the bushing and thus tothe vehicle chassis. The properties of claims 5 and 7 are directedtoward a particularly exact and dependable positioning of the bushingwithin the passage opening of the attachment section. Due to thelamellar construction of the ridges, their engagement points on theouter mantle surface of the bushing can be distributed more favorably.Because the lamellar ridges extend past the edge of the passage openingat one or at both outer surfaces of the attachment section, a solidconnection and a stable positional orientation of the lamina is achievedwith respect to the attachment section. Thus, any potential tilting ofthe bushing within the passage opening of the attachment section ismore! successfully counteracted than with ridges which have a nearlypoint-shaped cross section.

In another embodiment according to claim 8, a continuous lamina, whichas a whole bridges the annular gap between the bushing and the edge ofthe passage opening in the attachment section, appears instead ofseveral individual ridges or lamina. This design has the particularadvantage that the casting or injection-molding tool for the manufactureof the corresponding support portion of the windshield wiper system isless complicated and thus lower in cost than that for the previouslydescribed designs. In this case, however, it is necessary to inject orto cast the damping element from both sides into the attachment section.The damping element thus consists more or less of two separate partswhich are mutually separated by the closed lamina in the annular gap. Inorder to prevent as much as possible the transfer of sound or vibrationtransmitted through solids through the lamina in this kind of design,compared to a planar structure of the lamina, a corrugated or pleateddesign of the lamina according to claim 9 will be an advantage.

The mounting of a windshield wiper system of this kind on the vehiclechassis takes place in the conventional manner. A mounting bolt or amounting screw with corresponding washer is inserted through the bushingand screwed to the vehicle chassis. Since in the manufacture of thevehicle chassis and also in the manufacture of the windshield wipersystem, certain dimensional tolerances are required with regard to theattachment point for the windshield wiper system to the vehicle chassis,in practice partial attachment sections with an elongated passageopening can be used to hold a corresponding oval bushing and acorresponding oval damping element in order to compensate for thesetolerances. The present invention includes attachment features shaped inthis manner and thus it is not limited to a circular passage opening inthe attachment section of the windshield wiper system and to a dampingelement with annular cross section nor to a bushing with an annularcross section.

The invention will be explained in greater detail below based onembodiments. The figures show:

FIG. 1: A preassembled windshield wiper drive device presented inschematic, perspective view with the chassis parts to which the devicecan be attached,

FIG. 2: A top view of an attachment section of a windshield wiper drivedevice,

FIG. 3: A cross section along the line III--III from FIG. 2,

FIG. 4: A top view of another embodiment of an attachment section,

FIG. 5: A cross section along the line V--V in FIG. 4,

FIG. 6: An attachment section of a windshield wiper drive device withoutdamping element, shown in perspective view, and

FIG. 7: Another example of an attachment section without dampingelement, shown in perspective view.

FIG. 1 presents a windshield wiper drive device to be attached as apreassembled unit to the chassis of a motor vehicle, shown schematicallyin a partial view. The drive components needed to drive the wiper arms(not shown) are mounted on a support frame 1, which features aconnecting rod 2 at whose free ends there are bushing-like bearingelements 3 running transverse to this, of which only the left one isshown in FIG. 1. The bearing element 3 has at its outer perimeter anattachment protrusion 4 molded on, whose edge region is designed as anattachment section 5. A wiper shaft 6 can rotate in the bearing element3, but it is held axially and the wiper arm (not illustrated) isattached without rotational play. The wiper shafts 6 arranged at eitherend and connected by means of a multipart coupling linkage 7 whichconnects both wiper shafts 6 to the rotary motion synchronizer and isdriven by a crank 8 which is mounted without rotational play to thedrive shaft (not illustrated) of a drive motor 9. The drive motor 9 andits transmission, if any, are attached to a plate-like extender 10 whichis held against the connecting rod 2. In the vicinity of the edge of theextender 10 there is another attachment section 5.

For vibration-damping attachment of the windshield wiper drive unit tothe vehicle chassis, the attachment section 5 of the bearing element 3and the attachment section 5 of the extender 10 have an annular passageopening in which a hollow, cylindrically shaped elastomeric vibrationdamping element 11 is buttoned in. The preassembled windshield wiperdrive unit is attached in a known manner at the provided location in theengine compartment of the motor vehicle to chassis parts 13 intendedspecifically for this purpose; FIG. 1 shows two of them schematically.The chassis parts 13 have corresponding threaded holes 14, into whichthe attachment screws 12 can be screwed.

FIGS. 2 and 3 present one example of how a noise-damping orvibration-damping attachment feature can be designed for attachment of awindshield wiper system to a vehicle chassis. A support unit 15 of awindshield wiper system, which can have an attachment protrusion 4 of awiper bearing 3 of the kind shown in FIG. 1, has at one free end anattachment section 5 of relatively large thickness D. This attachmentsection 5 has a circular opening 16 and from its inner surface aperimeter rib 17 with thickness d extends inward and forms the perimeteredge of a circular passage opening 18. A hollow cylindrical bushing 19is positioned concentrically in the passage opening 18 and is connectedas a single piece by means of four ridges 20 to the attachment section 5of the support unit 15. The ridges 20 are of lamina-like design and havea vane-like appearance, that is, they are arc-shaped, between the casing19 and the attachment section 5. Relative to their width, thelamina-like ridges are arranged at a right angle to the plane passingthrough the rib 17. They exit roughly tangentially from the cylindrical,outer surface of the bushing 19 and extend up to the inside of theopening 16, in which they enter again roughly tangentially. Thus, thelamina extend past the edge of the passage opening 18 and are connectedon both sides to the rib 17. Due to this design, a dependable andprecise positioning of the casing 19 can be attained within the passageopening 18, whereby likewise a tilting of the casing 19 is effectivelyprevented.

The damping element 11 was produced by injection of elastomeric materialinto the space formed between the cylindrical, outer surface of thecasing 19 and the recess 16 including rib 17 and ridges 20, which wasadditionally bounded by a corresponding injection molding mold. Thus ithas an annular cross section and its volume encloses the rib 17 and theridges 20. In connection with the attachment of the windshield wiperdrive unit to the vehicle chassis, a mounting screw is inserted fromabove, using an intermediate washer of appropriate size, into thepassage opening 21 of the casing 19 and is then screwed to thecorresponding part of the chassis 13 (FIG. 1).

FIGS. 4 and 5 show another example of an attachment section 5 whichcorresponds in its essential parts to the example illustrated in FIGS. 2and 3. Therefore, a repetition of the description of these essentialparts will be omitted. The significant difference from the example ofFIGS. 2 and 3 is that now several, that is, four, spoke-like ridges 20with small round or even angular cross sections are distributeduniformly around the perimeter of the casing 13 and connect the casing19 with the interior edge of the rib 17. The ridges 20 are positionedradially and are thin enough so that they can hold the bushing 20 sic;19! in the desired position until after casting or injection-molding ofthe damping element 11, but can transmit hardly any sound or vibrations.It can even be an advantage to make the ridges very thin or to providethem with a set fracture point, so that they will break off, forexample, during assembly of the windshield wiper system to the vehiclechassis due to the occurring mechanical stress occurring thereby, or dueto a consciously applied mechanical stress, or so that they tear offfrom the bushing 19 or from the rib 17.

It is also possible for a single ridge 20 to be positioned essentiallyin the plane passing through the rib 17, provided as connector betweenthe casing 19 and the rib 17 of the attachment section 5. In this case,the ridge 20 is a single, closed, thin lamina, which seals the ring gapbetween the perimeter of the casing 19 and the edge of the passageopening. The damping element 11 now consists of an upper and a lowersection which are separated by the rib 17 and the ridge 20. There is nomaterial connection between the two parts of the damping element. Theinjection of the two parts of the damping element 11 likewise takesplace by injection molding in a corresponding mold; the injection mustoccur in two hollow mold cavities separated from each other by the ridge20. Otherwise, this connecting feature is handled exactly the same as inthe example described above. The advantage for an effective avoidance orlimitation of the transmission of solid-borne sound or vibration viathis ridge 20 is for the ridge 20 to be formed corrugated or pleatedwith respect to its radial width.

The design of an attachment section 5 illustrated in FIG. 6 is verysimilar to the example illustrated in FIGS. 2 and 3. In order better toillustrate the structure of the attachment section, a perspective modeof illustration was selected in FIG. 6 and the representation of thedamping element was left off. On the left side of the cut-awayrepresentation of FIG. 6 we see the bearing element 3 for a wiper shaft6 (FIG. 1) (not illustrated). At the outer perimeter of this bearingelement 3 on the right side, the attachment protrusion 4 is molded onwhich features an attachment section 5. The annular rib 17 is visible inthe opening 16; the edge 22 of this rib forms the circular passageopening 18. Within the passage opening 18 there is a concentric bushing19 which engages in the passage opening 18 and it is positioned withregard to its longitudinal direction nearly in the middle of thispassage opening 18. There are six ridges 20 arranged like vanesdistributed uniformly around the perimeter of the casing. The ridges 20are of lamina-like design and are aligned, with respect to their width,at a right angle to the rib 17. In addition, they exit at least roughlytangentially from the outer mantle surface of the bushing 19 and runarc-like in the direction of the inner wall of the circularcross-section opening 16. Thus they extend over the edge 22 of the rib17 and are also connected on both sides to the rib 17. The sides of theridges 20 turning away from the casing 19 in this case already end at adistance from the inner wall of the opening 16. It is thus evident thatthe entire element illustrated in FIG. 6 represents a single structuralelement manufactured as a single piece. In the manner already described(FIGS. 2 and 3) the component shown in FIG. 6 now needs to be completedby a damping element which is to be installed by means of injectionmolding directly in the attachment section 5.

FIG. 7 shows another example of an attachment section which is equippedwith essential properties of the example shown in FIGS. 4 and 5. Here,again, a repetition of the description of these already disclosedproperties is omitted. Thus, again, we see a bearing element 3 for awiper shaft (not illustrated) at whose perimeter there is a left-sideattachment lug 23 molded on (not entirely visible in this figure), withwhich the bearing element 3 can be attached free of rotational play tothe connecting rod 2 (FIG. 1) of a windshield wiper drive unit. On theright side, at the outer side of the bearing element 3, there is againan attachment protrusion 4 molded on, which has an attachment section 5.In a recess 16 in the region of the attachment section 5, there is againa ring-shaped rib 17 whose inner edge 22 also forms the circular passageopening 18. The bushing 19 extends through the passage opening 18 and ispositioned concentrically therein. The annular gap present between theedge 22 of the rib 17 and the perimeter of the bushing 19 is bridged bythe single, closed lamina, which functions as a ridge 20. The thin-wallridge 20 is thus designed so that it fully closes the aforesaid annulargap and connects the casing 19 with the rib 17. Accordingly, the entirecomponent represented in FIG. 7 is manufactured as a single piece.Analogous to FIG. 6, the component illustrated in FIG. 7 must becompleted by a damping element in its attachment section 5. As alreadydescribed in FIGS. 4 and 5, the damping element in this case would haveto consist of two mutually separated parts, each of which can beinjected separately from above or from below into the attachment section5. In the example shown in FIG. 7, the attachment screw is inserted frombelow into the passage opening 21 of the bushing 19.

We should mention that an attachment section 5 according to thisinvention can also be formed on an attachment plate, such as theextender 10 of the windshield wiper system (FIG. 1). It is not necessarythat the attachment section 5 have an opening 16 which bounds thedamping element 11 at its outer mantle surface. When using acorresponding injection mold, a damping element 11 can also be injectedin this case in the attachment section 5. The damping element 11 and thebushing 19 in this case protrude from both sides of the support platefeaturing the attachment section 5.

List of Reference Numbers

1 Support frame

2 Connecting rod

3 Bearing element

4 Attachment protrusion

5 Attachment section

6 Wiper shaft

7 Connecting linkage

8 Crank

9 Drive motor

10 Extender

11 Damping element

12 Attachment screw

13 Chassis part

14 Threaded hole

15 Support part

16 Opening

17 Rib

18 Passage opening

19 Bushing

20 Ridge

21 Passage opening

22 Edge

23 Attachment pin

D Thickness

d Thickness

We claim:
 1. A windshield wiper system with a noise-damping and vibration-damping attachment feature for attachment to a vehicle chassis, wherein a damping element is located in a passage opening of an attachment section of the windshield wiper system, and a bushing to hold an attachment means consisting of one element out of the group containing a bolt and a screw is located in a generally central passage opening of the damping element, whereina) the attachment section and the bushing are manufactured as a single part from the same material; b) the bushing is held by means of a single ridge at a distance from an edge of the passage opening of the attachment section and is at least temporarily connected via the single ridge to the attachment section, wherein said single ridge is in the form of a continuous lamina and bridges the annular gap between bushing and edge of the passage opening in the attachment section wherein the lamina is of ribbed form in the direction of the width of the annular gap between bushing and edge of the passage opening; and c) the material of the damping element is filled into the spaces between attachment section and bushing.
 2. A windshield wiper system with a noise-damping and vibration-damping attachment feature for attachment to a vehicle chassis, wherein a damping element is located in a passage opening of an attachment section of the windshield wiper system, and a bushing to hold an attachment means consisting of one element out of the group containing a bolt and a screw is located in a generally central passage opening of the damping element, whereina) the attachment section and the bushing are manufactured as a single part from the same material; b) the bushing is held by means of at least one ridge at a distance from an edge of the passage opening of the attachment section and is at least temporarily connected via the at least one ridge to the attachment section; c) the material of the damping element is filled into the space between attachment section and bushing wherein the at least one ridge has a set fracture point at which it will fracture under mechanical load.
 3. The windshield wiper system according to claim 2, wherein several ridges extend like spokes between the bushing and the attachment section.
 4. The windshield wiper system according to claim 2, wherein several ridges extend like vanes between the bushing and the attachment section.
 5. The windshield wiper system according to claim 2, wherein said at least one ridge has a bended shape.
 6. The windshield wiper system according to claim 2, wherein said at least one ridge includes a lamellar design.
 7. The windshield wiper system according to claim 2, wherein said at least one ridge runs at least approximately tangential into the outer mantle surface of the bushing.
 8. The windshield wiper system according to claim 2, wherein the component of the windshield wiper system which has the attachment section is manufactured as a metal cast article.
 9. The windshield wiper system according to claim 2, wherein the component of the windshield wiper system which has the attachment section is manufactured as an injection molded plastic article. 